1. Field of the Invention
The present invention relates to a damper mechanism that is installed as an accessory on an opening and closing member, such as a door or cover, which turns about a given axis of rotation.
2. Description of the Prior Art
When a door, cover or other opening and closing member which uses hinges is rotated or moved in one direction, such as the closing direction, and the member is automatically closed by such a rotating force, it is common practice to incorporate a damper mechanism which makes the member turn slowly to ensure the safety of the opening and closing movement and to ease the impact at the time of closure.
The simplest construction in prior-art damper mechanisms used for such a purpose is a single-action damper mechanism having a tubular, closed cylinder and a piston which fits inside the cylinder in a freely slidable manner and divides the interior of the cylinder into two chambers. The two chambers are made to communicate via an orifice provided in the piston. An urging member, such as a coil spring, which forces the piston in a first sliding direction is provided within one of the two chambers. In addition, a pressure-regulating valve which regulates the opening of the orifice according to the sliding direction of the piston is provided within the orifice. The pressure-regulating valve controls fluid pressure against the piston resisting the applied force. The base of the cylinder and the tip of the piston rod are respectively connected to a stationary side (which is a structure for receiving an opening and closing member) and a movable side (e.g. an opening and closing member such as a door). Generally, the coil spring acts to close the opening and closing member, in which state the pressure-regulating valve narrows the orifice, thereby slowly closing the member and suppressing the sound of impact at the time of closure.
In prior-art damper mechanisms, the piston which slides through the cylinder carries out linear motion. As a result, when the damper mechanism is mounted directly on an opening and closing member, it is inherently impossible to maintain a proportional relationship between the urging (e.g. applied) force by the damper mechanism and the degree of turning by the opening and closing member. Moreover, such a damper mechanism does not readily allow the member to be turned through a large angle, thus necessitating the installation of some kind of linking mechanism to facilitate opening and closing.
Prior-art damper mechanisms thus have a large number of parts, resulting in a high weight and high production costs. In addition, maintenance (e.g. maintainability) of prior art damper mechanisms is a problem due to the many moving parts.
It is desirable to provide a simple and convenient damper mechanism which can minimize the number of parts and has good maintainability.